Millions of American homeowners face foreclosure, but at least one sort of housing crisis has been remedied: No longer will research rats suffer the indignities of crowded cages. That is to say that the federal government has ordered labs to provide precisely measured living quarters for all rodents used in federally funded research. Thus, a female rat and her offspring must be housed (for their short, genetically altered lives) in lodgings that feature no less than 124 square inches of floor space and 7 inches of head room. By comparison, a mama mouse and her litter merit a mere 51-inch...